Disc Fusion Implant

ABSTRACT

An implant prosthesis is disclosed. In some cases, the prosthesis can take the form of an implant strip may be implanted through the use of a surgical procedure that minimizes incision sizes and may be considered less invasive than typical spinal implant procedures.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. application Ser. No.11/774,584, filed on Jul. 7, 2007, and entitled “Disk Fusion Implant”,the entirety of which is incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to implantable prostheses and inparticular to a spinal implant strip including a selectively appliedbone growth promoting agent.

2. Description of Related Art

Spinal fusion implants have been previously proposed. In some cases,spinal fusion implants are embedded between adjacent vertebrae,partially or fully replacing the tissue disposed between the vertebrae.

One type of spinal fusion implant is the threaded spinal implant(commonly referred to as a spinal cage). This type of prosthesis isdisclosed in Michelson (U.S. Pat. No. 6,264,656), the entirety of whichis incorporated by reference. The threaded spinal implant is insertedbetween two adjacent vertebrae and is incorporated into the fusion ofthe bone along this portion of the spine.

Brantigan (U.S. Pat. No. 4,834,757) discloses plugs, used as spinalfusion implants, the entirety of which is incorporated by reference. Theplugs are rectangular with tapered front ends and tool receiving rearends. Generally, the plugs may be used in a similar manner to the spinalcages of Michelson. As with the spinal cages, the plugs may be insertedbetween adjacent vertebrae. The plugs may include nubs that behave liketeeth, countering any tendency for the plugs to slip between thevertebrae.

Generally, the spinal fusion implants disclosed require invasive surgeryfor implantation. Furthermore, these spinal fusion implants rigidly fixtwo adjacent bones together and do not allow for any motion. There is aneed in the art for a type of spinal fusion implant that may beimplanted through a minimally invasive procedure. There is also a needfor fusion implants that can potentially accommodate motion.

SUMMARY OF THE INVENTION

A disc fusion implant is disclosed. In one aspect, the inventionprovides a spinal prosthesis, comprising: an implant strip including afirst shape and a second shape and wherein the first shape is differentthan the second shape; the first shape being configured for installationthrough a tube; and where the second shape is coiled.

In another aspect, the second shape is a coil.

In another aspect, the first shape is a strip.

In another aspect, the implant strip is made of a material includingtitanium.

In another aspect, the strip is a shape memory material.

In another aspect, the shape memory alloy is made of a material selectedfrom the group consisting essentially of: nickel, titanium, cobaltchrome, stainless steel, polymers, biological matrices and ceramics.

In another aspect, the invention provides a spinal prosthesis,comprising: an implant strip configured for insertion between twoadjacent vertebrae; and where the implant strip is a shape memory alloy.

In another aspect, the implant strip is a corrugated strip.

In another aspect, a plurality of strips are used.

In another aspect, three or more implant strips are used.

In another aspect, the invention provides a method of implanting aspinal prosthesis, comprising the steps of: making an incision in apatients back; inserting a tube into the incision; inserting the spinalprosthesis through the tube; and implanting the spinal prosthesisbetween two adjacent vertebrae.

In another aspect, the spinal prosthesis is an implant strip.

In another aspect, the tube includes a curved tip that is configured tofacilitate coiling of the implant strip.

In another aspect, the implant strip has a first shape and a secondshape.

In another aspect, the implant strip has the first shape when theimplant strip is inserted through the tube.

In another aspect, the implant strip has the second shape after theinsertion of the implant strip is completed.

In another aspect, the first shape is a flat strip.

In another aspect, the second shape is a coil.

In another aspect, the invention provides a spinal prosthesis,comprising: an implant strip configured for implantation between twoadjacent vertebrae; a bone growth promoting agent; and where the bonegrowth promoting agent is applied to the implant strip.

In another aspect, the implant strip includes a first portion.

In another aspect, the bone growth promoting agent is applied along thefirst portion.

In another aspect, the bone growth promoting agent is applied to theentirety of the implant strip.

In another aspect, the bone growth promoting agent is selectivelyapplied to the implant strip.

In another aspect, the bone growth promoting agent is applied to a topsurface of the implant strip and a bottom surface of the implant strip.

In another aspect, the invention provides a spinal prosthesis,comprising: an implant strip configured for insertion between twoadjacent vertebrae; the implant strip comprising a first portion havinga first rigidity and a second portion having a second rigidity that isless than the first rigidity; and where the second portion is configuredto deflect under an axial load.

In another aspect, the first portion is made of a substantiallynon-deforming material.

In another aspect, the second portion is made of a substantiallyflexible material.

In another aspect, the second portion has a modified structureconfigured to decrease the rigidity of the second portion.

In another aspect, the second portion includes a deflecting portion.

In another aspect, the deflecting portion has an elliptic shape.

In another aspect, the second portion includes a motion limiting tab.

In another aspect, the second portion includes a cross bar configured todeflect and limit the axial motion and lateral movement of the implantstrip.

In another aspect, the second portion is a protruding portion.

In another aspect, the protruding portion includes a plurality of slots.

In another aspect, the second portion is configured to partiallypermanently deflect.

In another aspect, the invention provides a spinal prosthesis configuredfor insertion between two adjacent vertebrae, a first vertebrae and asecond vertebrae, comprising: an implant strip including a lateraldimension extending from a first lateral side portion to a secondlateral portion, and wherein the implant strip includes a longitudinaldimension extending down the length of the implant strip; wherein thefirst lateral side of the implant strip is configured to engage thefirst vertebrae and wherein the second lateral side of the implant stripis configured to engage the second vertebrae; and wherein a firstlongitudinal portion of the implant strip forms a first inner coil, andwherein a second longitudinal portion of the implant strip forms asecond outer coil, wherein the second outer coil is spaced radiallyoutward of the first inner coil.

In another aspect, the first inner coil and the second inner coil arespaced to prevent contact with one another.

In another aspect, the first lateral side portion and the second lateralside portion comprise a first portion, and wherein a second portion isdisposed between the first lateral side portion and the second lateralside portion; and wherein the second portion is less rigid than thefirst portion.

In another aspect, the second portion permits motion between the firstlateral side portion and the second lateral side portion.

In another aspect, the first inner coil and the second inner coil arespaced to prevent contact with one another during motion.

In another aspect, the spinal prosthesis provides for continuity of aspine by providing a mechanical bridge between the first vertebrae andthe second vertebrae.

In another aspect, the spinal prosthesis also allows motion between thefirst vertebrae and the second vertebrae.

In another aspect, an elastomeric material is disposed between the firstlateral side portion and the second lateral portion, and wherein thefirst lateral side portion includes at least one protrusion engaging theelastomeric material.

In another aspect, the second lateral portion includes at least oneprotrusion engaging the elastomeric material.

Other systems, methods, features and advantages of the invention willbe, or will become, apparent to one of ordinary skill in the art uponexamination of the following figures and detailed description. It isintended that all such additional systems, methods, features andadvantages be included within this description and this summary, bewithin the scope of the invention, and be protected by the followingclaims.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention can be better understood with reference to the followingdrawings and description. The components in the figures are notnecessarily to scale, emphasis instead being placed upon illustratingthe principles of the invention. Moreover, in the figures, likereference numerals designate corresponding parts throughout thedifferent views.

FIG. 1 is an isometric view of a preferred embodiment of a patientundergoing surgery;

FIG. 2 is a plan view of a preferred embodiment of an intervertebraldisc;

FIG. 3 is a schematic view of a preferred embodiment of a healthyintervertebral disc and an intervertebral disc that has degenerated;

FIG. 4 is a plan view of a preferred embodiment of an implant strip;

FIG. 5-1 is a cross sectional view of a preferred embodiment of animplant strip with a bone growth promoting agent applied to the surface;

FIG. 5-2 is a cross sectional view of a preferred embodiment of animplant strip with a bone growth promoting agent that is selectivelyapplied to the surface;

FIG. 6 is a plan view of a preferred embodiment of an intervertebraldisc with a surgical tool and a dual catheter inserted;

FIG. 7 is a plan view of a preferred embodiment of an intervertebraldisc with an implant strip being inserted;

FIG. 8 is a plan view of a preferred embodiment of an implant stripfully inserted;

FIG. 9 is a plan view of a preferred embodiment of an intervertebraldisc including three implant strips;

FIG. 10 is a plan view of a preferred embodiment of an intervertebraldisc with a corrugated implant strip inserted;

FIG. 11 is a schematic view of a preferred embodiment of an implantdevice in a pre-deflection state and a post-deflection state;

FIG. 12 is a schematic view of a preferred embodiment of an implantdevice undergoing bending;

FIG. 13 is a schematic view of a preferred embodiment of an implantdevice undergoing translation;

FIG. 14 is a schematic view of a preferred embodiment of an implantdevice undergoing twisting;

FIG. 15 is an isometric view of a preferred embodiment of an implantstrip;

FIG. 16 is an isometric view of a preferred embodiment of an implantstrip that has coiled;

FIG. 17 is an isometric view of a preferred embodiment of a coiledimplant strip under axial force;

FIG. 18 is a plan view of a preferred embodiment of a section of animplant strip configured for axial deflection;

FIG. 19 is a plan view of a preferred embodiment of a section of animplant strip under axial load;

FIG. 20 is a plan view of a preferred embodiment of a section of animplant strip configured for axial deflection;

FIG. 21 is a plan view of a preferred embodiment of a section of animplant strip under axial load;

FIG. 22 is a plan view of a preferred embodiment of a section of animplant strip configured for axial deflection;

FIG. 23 is a plan view of a preferred embodiment of a section of animplant strip under axial load;

FIG. 24 is a plan view of a preferred embodiment of a section of animplant strip configured for axial deflection;

FIG. 25 is a plan view of a preferred embodiment of a section of animplant strip under axial load;

FIG. 26 is an isometric view of a preferred embodiment of an implantstrip with slots;

FIG. 27 is a cross sectional view of a preferred embodiment of animplant strip with slots;

FIG. 28 is a cross sectional view of a preferred embodiment of animplant strip with slots;

FIG. 29 is an isometric view of a preferred embodiment of a coiledimplant strip with slots;

FIG. 30 is a top view of a preferred embodiment of a coiled implantstrip with slots;

FIG. 31 is an isometric view of a preferred embodiment of an implantstrip undergoing axial deflection;

FIG. 32 is a plan view of two preferred embodiments of implant stripswith slots with a differing number of slots;

FIG. 33 is a plan view of two preferred embodiments of implant stripswith slots undergoing circumferential deflection;

FIG. 34 is a plan view of a preferred embodiment of an implant stripwith different slots;

FIG. 35 is a schematic view of a preferred embodiment of an implantstrip partially permanently deflecting;

FIG. 36 is a plan view of a preferred embodiment of a delivery deviceused for facilitating coiling of an implant strip;

FIG. 37 is a top down view of a preferred embodiment of a herniatedintervertebral disc;

FIG. 38 is a top down view of a preferred embodiment of a herniated discafter partial discectomy; and

FIG. 39 is a top down view of a preferred embodiment of a herniated discwith an implant strip inserted.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 is an isometric view of a preferred embodiment of patient 1100 onoperating table 1102. In this embodiment, patient 1100 is experiencing asurgical procedure to insert a spinal prosthesis. In particular, back1104 of patient 1100 preferably includes first incision 1106 and secondincision 1108. In a preferred embodiment, first incision 1106 includesfirst tube 1110 and second incision 1108 includes second tube 1114.Preferably, first incision 1106 and second incision 1108 are both lessthan one inch long. It should be understood that the placement ofincisions 1106 and 1108 may be moved further together or closer apartand the location of incisions 1106 and 1108 in the current embodiment isonly meant to be exemplary.

Preferably, first tube 1110 and second tube 1114 may be inserted into anintervertebral disc disposed between two adjacent vertebrae. FIG. 2 is aplan view of a single vertebra, shown generally at 1200, and anassociated intervertebral disc 1202. (The anatomy shown in FIG. 2 isgenerally that of a lumbar vertebra, although the anatomy of thoracic,lumbar and cervical vertebra is similar; therefore, FIG. 2 can beconsidered to illustrate the basic principles of thoracic, lumbar andcervical vertebral anatomy.) The spinous process 1206 of the vertebra1200 extends dorsally and can typically be palpated and felt through theskin of the back. Also in the dorsally-extending portion of the vertebra1200 are two transverse processes 1208 and two mammillary processes andfacet joints 1212. A spinal canal 1214 (i.e., an opening) is provided inthe vertebra 1200. The spinal cord and nerves 1216 extend through thespinal canal 1214 such that the spinal cord 1216 receives the fullprotection of the bony, dorsally-located spinous, transverse, andmammillary processes and facet joints 1206, 1208, 1212. The vertebralbody also protects the spinal cord and nerves 1216 ventrally.Periodically, nerves 1218 branch out from the spinal cord 1216 toinnervate various areas of the body. The forward or ventral edge of thevertebral foramen 1221 is defined by the vertebral body (not shown inFIG. 2), a bony, generally elliptical shelf in front of which theintervertebral disc 1202 rests. FIG. 2 also illustrates the basicstructure of the intervertebral disc 1202, including the annulusfibrosis 1222 and the nucleus pulposus 1224.

In some cases, an intervertebral disc 1202 may degenerate over time,requiring the need for a spinal disc implant. FIG. 3 illustrates apreferred embodiment of degeneration. In this embodiment, healthyintervertebral disc 302 is disposed between vertebrae 304. In this case,vertebrae 304 are separated by a distance D1 because of support providedby disc 302. Also shown in FIG. 3 is unhealthy intervertebral disc 306,which is disposed between vertebrae 308. In this case, vertebrae 308 areseparated by a distance D2 that is much smaller than distance D1 becauseof the degeneration of disc 306.

If an intervertebral disc has failed or degenerated, a typicalcorrection is a surgical procedure to remove some or all of theintervertebral disc. Following this, a spinal prosthesis may be insertedin order to facilitate fusion of the vertebrae adjacent to the failedintervertebral disc. In a preferred embodiment, surgery may be performedin a manner that limits the size of the incisions needed to insert aprosthesis. Preferably, a spinal prosthesis includes provisions for easyinsertion via a small incision in the back.

In some cases, a vertebral body could also be fully or partiallyreplaced using a spinal prosthesis. The following detailed descriptionrefers to the replacement of an intervertebral disc, however in otherembodiments these same principles could be applied to a spinalprosthesis configured to replace a vertebral body.

FIGS. 4 and 5 illustrate a preferred embodiment of implant strip 1400.Generally, implant strip 1400 may be a long thin strip. Preferably,implant strip 1400 has a length L1 much greater than a width W1.Additionally, the thickness T1 of implant strip 1400 is preferably smallcompared to both the length and the width of implant strip 1400. In someembodiments, length L1 may be between 1 cm and 100 m. In someembodiments, width W1 may be between 2 mm and 20 cm. In someembodiments, thickness T1 may be between 0.01 mm and 3 mm. It should beunderstood that if a vertebral body is being replaced, the thickness ofimplant strip 1400 could be much larger than the values discussed here.

As implant strip 1400 preferably has a relatively small profile, it maybe inserted into smaller incisions, such as those shown in FIG. 1.However, to provide adequate support to the adjacent vertebrae, implantstrip 1400 may preferably be packed tightly into intervertebral disc1202. In some embodiments, the packing of implant strip 1400 may betight or loose depending upon mechanical properties of implant strip1400. For this reason, implant strip 1400 preferably includes provisionsfor conforming to a packed shape once it has been inserted intointervertebral disc 1202.

Generally, implant strip 1400 may be constructed of a material includingmetal. In some embodiments, implant strip 1400 may be a shape memoryalloy. In some embodiments, implant strip 1400 may be made of a titaniumalloy. In other embodiments, implant strip 1400 may comprise acombination of one or more materials including, but not limited to,cobalt chrome (CoCr), stainless steel, Nitinol, polymers, biologicalmatrices, ceramics or any biocompatible material. In a preferredembodiment, implant strip 1400 may be made of a material includingtitanium.

In some cases, a stainless steel alloy may be used as a coiling spring.This arrangement is useful because such alloys low fatigue and highfatigue resistance. Additionally, these alloys may have a high returnforce. Additionally, using a stainless steel alloy allows for increasedcorrosion resistance.

Preferably, implant strip 1400 may include provisions for changingshape. In some embodiments, implant strip 1400 may be manufactured at anelevated temperature with a first shape. Following this, implant strip1400 may be cooled and deformed into a second shape. Finally, as implantstrip is placed in temperature ranges of 90-100 degrees Fahrenheit, itmay deform back to the first shape. In a preferred embodiment, the firstshape is a spiral coil and the second shape is a long rectangular strip.

In some embodiments, implant strip 1400 may include provisions forpromoting bone growth, once it has been inserted into the intervertebraldisc region. In some embodiments, implant strip 1400 may include a bonegrowth promoting agent. In a preferred embodiment, implant strip 1400preferably includes bone growth promoting agent 1402 disposed along theentirety of its length. FIG. 5-1 is a cross sectional view of implantstrip 1400 with bone growth promoting agent 1402 disposed along itsentire outer surface 1401.

In some embodiments, bone growth promoting agent 1402 may be selectivelyapplied to one or more portions of implant strip 1400 or may not beapplied at all. Preferably, as shown in FIG. 5-2, bone growth promotingagent 1402 may be applied to top surface 1403 of outer surface 1401.Likewise, bone growth promoting agent 1402 may also be applied to bottomsurface 1405 of outer surface 1401. Generally, any type of bone growthpromoting agent may be applied and in any pattern. Methods forselectively applying bone growth promoting agents have been previouslydisclosed in U.S. Pat. No. ______, now U.S. patent application Ser. No.11/740,181, the entirety of which is hereby incorporated by reference.

Details of a preferred embodiment of a surgical procedure used to inserta spinal prosthesis of some kind are best understood with respect toFIGS. 6-8. The following embodiment comprises steps for inserting aspinal prosthesis using two tubes, however it should be understood thatin other embodiments, a single tube may be used for discectomy and/orimplantation. In this case, any parallel steps involving the use of twotubes simultaneously could be performed sequentially with a single tube.In particular, steps using a camera and/or light inserted through onetube and a spinal tool through a second tube may be accomplished byusing a single tube incorporating a light and/or camera at the peripheryof the tube or just outside of the tube.

In a first step, first tube 1510 and second tube 1514 may be insertedinto intervertebral disc 1202. Generally, one tube may be used for asurgical tool, while the second tube may be simultaneously used toinsert a fiber optic camera into one of the incisions to give thesurgeon a clear view of the intervertebral disc region. In someembodiments, first tube 1510 and second tube 1514 may be cannulae. Thecross sectional shape of tubes 1510 and 1514 may be any shape, includingoval-like, circular or otherwise round, as well as hexagonal or anypolygonal shape.

Following the insertion of first tube 1510 and second tube 1514, aseries of instruments may be used to remove portions of intervertebraldisc 1202 and score the endplates. In some embodiments, first surgicaldevice 1540 may be inserted into first tube 1510. First surgical device1540 may be a brush, burr, rasp or a shaver. In a preferred embodiment,first surgical device 1540 may include flexible shaft 1542 and wirebrush tip 1544. Preferably, wire brush tip 1544 spins, removing portionsof intervertebral disc 1202.

In some embodiments, dual catheter 1550 may be inserted into second tube1514. Preferably, dual catheter 1550 may include first channel 1552 andsecond channel 1554. In some embodiments, first channel 1552 may includea fiber optic camera. With this configuration, the surgery may bevisualized by the surgeon using the fiber optic camera. Additionally,second channel 1554 may be configured to inject water and/or provide avacuum for removing debris. With this configuration, second channel 1554may be used to clean out cavity 1560, which is created as a portion ofintervertebral disc 1202 is removed. Once the necessary portions ofintervertebral disc 1202 have been removed, first surgical device 1540may be removed from first tube 1510.

Referring to FIGS. 7-8, implant strip 1400 may be inserted into cavity1560 once a portion of intervertebral disc 1202 has been removed. Aspreviously discussed, implant strip 1400 preferably has a materialstructure that allows it to change shape following insertion into cavity1560. In a preferred embodiment, implant strip 1400 is configured tocoil as it is exposed to temperatures between 90 and 100 degreeFahrenheit. In other embodiments, implant strip 1400 could coil due tonon-temperature dependent memory, such as occurs with a measuring tape.This could be achieved using a titanium implant strip, for example.

In this embodiment, first portion 1600 of implant strip 1400 has startedto coil as it is inserted into cavity 1560. Preferably, as implant strip1400 is further inserted through first tube 1510, the portion disposedwithin cavity 1560 may deform and coil as well. In a preferredembodiment, implant strip 1400 may be inserted in a manner that allowsimplant strip 1400 to coil around itself completely, as seen in FIG. 8.

Generally, implant strip 1400 may be configured to fill cavity 1560 ofintervertebral disc 1202 completely. For illustrative purposes, implantstrip 1400 is shown here to be coiled with large gaps between adjacentportions. However, in some embodiments, implant strip 1400 may be coiledtightly so that no gaps are seen. In a preferred embodiment, implantstrip 1400 may be coiled loosely to provide space or gaps betweenadjacent, radially spaced coils. This arrangement may help to facilitatebone growth to occur between the coils.

In an alternative embodiment, multiple implant strips may be used.Preferably, each implant strip may include a coiled shape, similar tothe shape of the previous embodiment. In some embodiments, each of theimplant strips may be disposed against one another. In some embodiments,each of the implant strips may be associated with different heights inorder to create lordosis.

FIG. 9 is a preferred embodiment including multiple implant stripsinserted within cavity 1560. In this embodiment, first implant strip1802, second implant strip 1804 and third implant strip 1806 have beeninserted into cavity 1560. Preferably, each of the implant strips1802,1804 and 1806 may be inserted in an identical manner to the methodused to insert the implant strip of the previous embodiment. Generally,any number of implant strips may be inserted into cavity 1560.

Preferably, each of the implant strips 1802, 1804 and 1806 may beconstructed of a shape memory alloy. In some embodiments, the shapememory alloy may be a nickel titanium alloy. In other embodiments,implant strips 1802, 1804 and 1806 may comprise a combination of one ormore materials including, but not limited to, cobalt chrome (CoCr),stainless steel, Nitinol, polymers, biological matrices, ceramics or anybiocompatible material. In a preferred embodiment, implant strips 1802,1804 and 1806 may be made of a material including titanium.

In other embodiments, the structure of an implant strip may be modified.In some embodiments, an implant strip may include a slightly differentshape. In other embodiments, an additional material may be used inconjunction with the shape memory alloy of the previous embodiments.

FIG.10 is a preferred embodiment of corrugated implant strip 1902, whichhas been inserted into cavity 1560. Preferably corrugated implant strip1902 includes small bends along its length. Preferably, corrugatedimplant strip 1902 may be inserted into cavity 1560 in an identicalmanner to the method used to insert the previously discussed implantstrips. As with the previous embodiments, it should be understood that abone growth promoting agent may be applied to corrugated implant strip1902. This arrangement allows for greater mechanical strength as well asfor facilitating increased bone growth into implant strip 1902. Byproviding increased surface area, this arrangement may facilitategreater bone growth and more rapid bone healing.

Preferably, corrugated implant strip 1902 may be constructed of a shapememory material. In some embodiments, the shape memory alloy may be anickel titanium alloy. In a preferred embodiment, corrugated implantstrip 1902 may be made of a material including titanium. Generally,corrugated implant strip 1902 may be made of any of the materialsdiscussed with respect to the previous embodiments of implant strips,including cobalt chrome (CoCr), stainless steel, Nitinol, polymers,biological matrices, ceramics or any biocompatible material.

Preferably, an implant device includes provisions for allowing fordifferent kinds of motion that may occur in a spine.

In some embodiments, an implant device may include provisions toaccommodate deflections in the axial direction. This may be a usefulfeature as axial forces may be applied to the implant strip by theadjacent vertebrae during normal activities such as walking, running andbending of the spinal column. In other words, the implant strip may beconfigured to endure axial loads that are usually applied to spinaldiscs. Additionally, the implant device may be configured to accommodatebending, lateral (including shear forces), and twisting forces.

FIGS. 11-14 are intended to illustrate a generic embodiment of implantdevice 2200. Generally, implant device 2200 may be any kind of deviceconfigured for implantation into the human body. In some cases, implantdevice 2200 may be configured to be implanted between vertebrae,functioning as a full or partial disc replacement device. In a preferredembodiment, implant device 2200 may be an implant strip.

FIG. 11 is intended to illustrate a general embodiment of implant device2200 in a pre-deflection state 2210 and a post-deflection state 2212. Inthis embodiment, implant device 2200 includes first portion 2202 andsecond portion 2204. Preferably, first portion 2202 is relatively rigidcompared to second portion 2204. In other words, second portion 2204 isconfigured to deflect under axial forces before first portion 2202 woulddeflect. As shown in FIG. 11, second portion 2204 has a first height H1in a pre-deflection state 2210 and a second height H2 in apost-deflection state 2212. First height H1 is preferably greater thansecond height H2. Additionally, first portion 2202 and second portion2204 have a third combined height H3, in pre-deflection state 2210 and afourth combined height H4 in post-deflection state 2212. Third combinedheight H3 is preferably greater that fourth combined height H4. Thispreferred arrangement allows for some deflection of implant device 2200without causing fatigue or failure.

In addition to deflection in the axial direction, a spinal implantdevice may also be configured to undergo bending, lateral and twistingmotions. Implant device 2200 is seen in FIG. 12 to undergo a bendingmotion due to bending forces 2209. As bending forces 2209 are applied tofirst portion 2202, second portion 2204 may bend. This preferredarrangement allows for some bending of implant device 2200 withoutcausing fatigue or failure.

Implant device 2200 is seen in FIG. 13 undergoing a lateral motion dueto a lateral force 2208. As lateral force 2208 is applied to firstportion 2202, second portion 2204 may be deflected laterally. Thispreferred arrangement allows for some lateral deflection of implantdevice 2200 without causing fatigue or failure.

Referring to FIG. 14, implant device 2200 is seen in undergoing atwisting motion due to a rotational force 2210. As rotational force 2210is applied to first portion 2202, second portion 2204 may be twisted.This preferred arrangement allows for some twisting of implant device2200 without causing fatigue or failure.

In each of these cases, first implant devices 2200 is provided withrestoring forces via second portion 2204. Additionally, although thesedifferent types of deflections (due to compressive, bending, twistingand lateral forces) have been shown separately, it should be understoodthat implant device 2200 may be configured to undergo any combination ofor all of these various types of deformations simultaneously.

First portion 2202 may be made of any material, including both shapememory alloys and spring steel, as well as other types of materials,including previously discussed materials for implant strip 1400. Secondportion 2204 may be made of any material that may be less rigid thanfirst portion 2202. In addition, second portion 2204 may be designed todeflect and/or deform under various forces. Examples of such materialsinclude, but are not limited to, elastomers, soft metals, plastics,polymers, wire meshes (made from materials such as Dacron or ceramics),as well as other types of materials.

Additionally, in some embodiments, first portion 2202 and second portion2204 could be made of the same material. However, the rigidity of secondportion 2204 could be modified by changing the structural properties ofsecond portion 2204. This configuration may be achieved by insertingholes or slots or modifying the structure of second portion 2204 inother ways. With these types of modifications, first portion 2202 may bemore rigid than second portion 2204 even though they are made of thesame material.

Preferably, the degree of deflection of implant device 2200 may vary.During the initial implantation, implant device 2200 may deflect orcompress until the height of the implant device is about eighty percentof the initial height of the implant strip prior to implantation. Thisinitial deflection is primarily due to normal stresses applied by theadjacent vertebrae when the spinal column is at rest. During motion,however, implant device 2200 may continue to deflect due to increasedaxial loads from the adjacent vertebrae. The degree of deflection may bebetween 15 and 25 percent of the initial height of implant device 2200.It should be understood, however, that the degree of deflection is notlimited and may vary according to properties of the various materialsthat are used. In some cases, the degree of deflection could be muchlarger than 25 percent or much less that 15 percent. By carefullyselecting the material, size, design as well as other structuralfeatures of second portion 2204, the deflection of implant device 2200can be better controlled. The following embodiments illustrate ways inwhich the deflection of implant device 2200 can be achieved usingdifferent materials and structural features for second portion 2204.

FIG. 15 is an isometric view of a preferred embodiment of implant strip2000. In some embodiments, implant strip 2000 may extend in a lateraldirection from a first lateral side portion 2002 to a second lateralside portion 2006. Preferably, first lateral side portion 2002 andsecond lateral side portion 2006 may be constructed of a similarmaterial to the implant strips of the previous embodiments. Inparticular, side portions 2002 and 2006 may be made of a substantiallyrigid material that does not deflect much under axial loads.

In some embodiments, elastomer strip 2004 may be disposed between firstlateral side portion 2002 and second lateral side portion 2006.Elastomer strip 2004 is preferably made of a flexible material. In someembodiments, elastomer strip 2004 may be joined to first lateral sideportion 2002 and second lateral side portion 2006. In some embodiments,elastomer strip 2004 may encase perforated edges, teeth or roughed edgesof first lateral side portion 2002 and second lateral side portion 2006in order to ensure a positive mechanical connection. In this preferredembodiment, first lateral side portion 2002 and second lateral sideportion 2206 may be associated with teeth 2007. Using thisconfiguration, teeth 2007 provide a point of attachment for elastomerstrip 2004 to first lateral side portion 2002 and second lateral sideportion 2006. In other embodiments, other provisions may be used tofixedly attach elastomer strip 2004 to first lateral side portion 2002and second lateral side portion 2006.

In some embodiments, implant strip 2000 may include a bone growthpromoting agent. In this embodiment, top portion 2003 and bottom portion2005 are preferably coated with a bone growth promoting agent 2001.Generally, any type of bone growth promoting agent may be used.Additionally, any type of pattern for a bone growth promoting agent maybe used. Various bone growth promoting agents and patterns have beenpreviously referenced. Using this configuration, implant strip 2000 maybe configured to stimulate increased bone growth at adjacent vertebraewhere implant strip 2000 is implanted. In some embodiments, such aconfiguration may be used in a manner similar to a spinal cage, whichprovides a means of fusing two vertebral bodies together.

FIGS. 16 and 17 are a preferred embodiment of implant strip 2000 afterit has been coiled. Initially, implant strip 2000 has an axial heightH5. As axial force 2012 is applied to flexible implant strip 2000,elastomer strip 2004 may deflect in the axial direction, allowing firstlateral side portion 2002 and a second lateral side portion 2006 tosqueeze together. In this embodiment, flexible implant strip 2000 has aheight H6 that is less than height H5 following axial deflection.Generally, elastomer strip 2004 has deformed and may slightly bulgeoutwards. This preferred arrangement allows implant strip 2000 todeflect under axial forces applied by adjacent vertebrae followingimplantation, which provides a similar function to a spinal disc. Also,using this configuration flexible implant strip 2000 may be configuredas a flexible spiral coil that may not escape containment. Preferably,using this arrangement, the adjacent vertebrae may engage lateral sideportions 2002 and 2006 of implant strip 2000 to lock it into place.

Referring to FIGS. 15-17, implant strip 2000 preferably is configured tobe coiled in a manner that prevents contact between adjacent coils. Inthis embodiment, implant strip 2000 may include first longitudinalportion 2080 and second longitudinal portion 2081 extending in alongitudinal direction down the length of implant strip 2000, as seen inFIG. 15. First longitudinal portion 2080 extends from first boundary2082 to second boundary 2083. Second longitudinal portion 2081 extendsfrom second boundary 2083 to third boundary 2084. Generally, the lengthsof each longitudinal portion 2080 and 2081 are approximately equal toone 360 degree turn of a coil when implant strip 2000 is in a coiledstate. In this embodiment, longitudinal portions 2080 and 2081 areadjacent to one another, however in other embodiments longitudinalportions 2080 and 2081 may not be adjacent to one another.

Preferably, first longitudinal portion 2080 is configured to form afirst inner coil 2086, as seen in FIGS. 15-17, as implant strip 2000deforms to a coiled shape. Likewise, second longitudinal portion 2081 isconfigured to form a second outer coil 2087. In a preferred embodiment,second outer coil 2087 is spaced radially outward from first inner coil2086. In some embodiments, first inner coil 2086 and second outer coil2087 are spaced apart by a radial distance R5 when first lateral sideportion 2002 and second lateral side portion 2006 are not in motion (seeFIG. 16). Generally, distance R5 may have any value and may vary fromone embodiment to another. Using this preferred arrangement, first innercoil 2086 and second outer coil 2087 are spaced to prevent contact withone another. Preferably, first inner coil 2086 and second outer coil2087 are also spaced apart when first lateral side portion 2002 andsecond lateral side portion 2006 are in motion, such as when implantstrip 2000 is in a compressed or axially deflected state (see FIG. 17).This arrangement helps to reduce or substantially eliminate particulatedebris that may result from the rubbing of various portions togetherover the lifetime of implant strip 1400.

Preferably, provisions for preventing contact between portions of animplant strip may be provided in other embodiments as well. Theprinciples discussed here may be generally applied to any type ofimplant strip including a first longitudinal portion and a secondlongitudinal portion. In some embodiments, these implant strips may ormay not include deforming portions.

In other embodiments, an implant strip may include different provisionsfor allowing deflection of the implant strip in the axial direction. Insome embodiments, an implant strip may include perforated portions withlarge gaps or holes that reduce rigidity and thereby allow for somedeflection of the implant strip. It should be understood that throughoutthese embodiments, illustrated in FIGS. 18-34, the various implantstrips include portions of differing rigidity. Furthermore, in each ofthese embodiments, the portions of differing rigidity are joinedtogether.

FIGS. 18-25 are preferred embodiments of sections of spinal implantstrips that are configured for various types of deflection, includingaxial deflection. The spinal implant strips are also capable ofaccommodating other types of deflection, including bending, twisting andlateral shear. Throughout these embodiments, it should be understoodthat the implant strips may be made of any material configured to coilor deflect in the circumferential direction. In some embodiments, thesesections of implant strips may be made of a single material or comprisea combination of one or more materials including, but not limited to,cobalt chrome (CoCr), stainless steel, Nitinol, polymers, biologicalmatrices, ceramics or any biocompatible material. In a preferredembodiment, these sections of implant strips may be made of a materialincluding titanium.

FIG. 18 is a preferred embodiment of a portion of first implant strip2020 prior to deflection. First implant strip 2020 preferably includeslower edge 2002 and upper edge 2006. Lower edge 2002 and upper edge 2006are preferably thin strips that form an outer periphery for firstimplant strip 2020.

Additionally, first implant strip 2020 may include first deflectingportions 2024 that are disposed between lower edge 2002 and upper edge2006. Preferably, lower edge 2002 and upper edge 2006 are joined tofirst deflecting portions 2024. For purposes of clarity, only a sectionof first implant strip 2020 is shown here, however it should beunderstood that first deflecting portions 2024 are preferably disposedalong the entire length of first implant strip 2020. Generally, thespacing and number of first deflecting portions 2024 may be varied inorder to change the deflection properties of first implant strip 2020.

In this embodiment, first deflecting portions 2024 may be ellipticallyshaped prior to deflection. In other embodiments, the shape of firstdeflecting portions 2024 may vary. Examples of other shapes that may beused include, but are not limited to, circles, diamonds, as well as anypolygonal shape. Additionally, in other embodiments, the thicknessassociated with first deflecting portions 2024 could be changed. Byvarying these properties of first deflecting portions 2024, thedeflection properties of first implant strip 2020 may be modified.

In some embodiments, first implant strip 2020 may also include motionlimiting features that prevent excessive deflection in the axialdirection. In this embodiment, first implant strip 2020 may includemotion limiting tabs 2026. Preferably, motion limiting tabs 2026 may bedisposed between edges 2002 and 2006. Furthermore, motion limiting tabs2026 may be disposed within deflecting portions 2024 and/or adjacent todeflecting portions 2024.

Preferably, deflecting portions 2024 and motion limiting tabs 2026 maybe formed by cutting or removing portions of first implant strip 2020,which creates gaps within interior space 2022. This cutting may be doneusing techniques known in the art, such as stamping, punching, laserfusion and/or water drilling, or any combination of techniques. In otherembodiments, first implant strip 2020, including deflecting portions2024 and tabs 2026 may be formed using a die of some kind. Thesetechniques are preferably used to create smooth edges in order toprevent burrs. Using this configuration, scar tissue due to burrs may besubstantially reduced following implantation of first implant strip2020. In other embodiments, however, techniques used that leave burrsintact may be used so that the remaining burrs may facilitate in-growthof bone.

Following the insertion of first implant strip 2020 between two adjacentvertebrae, an axial force may be experienced as the vertebrae arecompressed during motion of the spinal column. Referring to FIG. 19,first deflecting portions 2024 may be compressed under axial force 2028.As first deflecting portions 2024 compress, lower edge 2002 and upperedge 2006 move closer together. As previously discussed, excessive axialdeflection may be prevented using motion limiting tabs 2026. Preferably,tabs 2026 are substantially rigid and therefore will not deflect ordeform under axial force 2028. Therefore, as tabs 2026 make contact, thecompression of first deflecting portions 2024 may cease. In thisembodiment, the height of implant strip 2020 has been modified from anoriginal height H3 to a modified height H4 that is less than H3. Onceaxial force 2028 has been removed or reduced, implant strip 2020 mayexpand in the axial direction as deflecting portions 2024 uncompress.Using tabs 2026 helps to prevent fatigue failure of deflecting portions2024 by limiting the range of motion.

Referring to FIGS. 20-25, an implant strip may include different typesof deflecting portions. Additionally, an implant strip may or may notinclude motion limiting tabs. In a second embodiment, seen in FIGS.20-21, second implant strip 2030 includes first deflecting ellipse 2032,second deflecting ellipse 2034 and third deflecting ellipse 2036disposed between edges 2002 and 2006 and within interior space 2038.Preferably, ellipses 2032, 2034 and 2036 are joined to edges 2002 and2006. As axial force 2028 is applied, deflecting ellipses 2032, 2034 and2036 are compressed until they obtain a substantially circular shape. Atthis point, ellipses 2032, 2034 and 2036 are disposed against oneanother, which may prevent any further deflection or deformation in theaxial direction.

In a third embodiment, shown in FIGS. 22-23, third implant strip 2040includes fourth deflecting ellipse 2042 and fifth deflecting ellipse2046 disposed between edges 2002 and 2006 and within interior space2048. Preferably, ellipses 2042 and 2046 are joined to edges 2002 and2006. In addition, third implant strip 2040 preferably includes crossbar 2044 that is disposed between fourth deflecting ellipse 2042 andfifth deflecting ellipse 2046. Cross bar 2044 preferably connects toboth lower edge 2002 and upper edge 2006. In a preferred embodiment,deflecting ellipses 2042 and 2046 as well as cross bar 2044 may alldeflect under axial force 2028. In particular, cross bar 2044 mayexperience column deflection. Preferably, cross bar 2044 only partiallydeflects, which limits the axial motion of lower edge 2002 and upperedge 2006.

In a fourth embodiment, seen in FIGS. 24-25, fourth implant strip 2050includes first curved portion 2052 and second curved portion 2056.Preferably, curved portions 2052 and 2056 are joined to edges 2002 and2006. Fourth implant strip 2050 also preferably includes motion limitingtabs 2054. As axial force 2028 is applied to fourth implant strip 2050,curved portions 2052 and 2056 may deflect in the axial direction.Preferably, as tabs 2054 make contact, the deflection of lower edge 2002towards upper edge 2006 may cease. Additionally, curved portions 2052and 2056 may contact edges 2002 and 2006, preventing further deflection.

FIGS. 26-28 illustrate another preferred embodiment of implant strip2300 that is configured for axial deflection. Implant strip 2300includes upper side 2304 and lower side 2306 that extend vertically.Protruding portion 2303 preferably extends outwards from, and ispreferably joined with, upper side 2304 and lower side 2306. Inparticular, protruding portion 2303 includes first sloped portion 2310and second sloped portion 2312 as well as flat portion 2308. Using thispreferred arrangement, implant strip 2300 may be configured for slightdeflections in the axial direction, as some slight compression ofimplant strip 2300 may occur at protruding portion 2303. In particular,as axial loads are applied to implant strip 2300, the angle of firstsloped portion 2310 and second sloped portion 2312 with respect to upperside 2304 and lower side 2306 may vary.

FIG. 28 illustrates an alternative embodiment of a cross sectional viewof protruding portion 2303. In the embodiment shown in FIG. 27, firstsloped portion 2310 and second sloped portion 2312 are straightportions. Alternatively, protruding portion 2303 could include firstcurved portion 2320 and second curved portion 2322. Using an alternativeshape for protruding portion 2303 allows for changes in the deflectingproperties of implant strip 2300. In other embodiments, the shape ofprotruding portion 2303 could be further modified to change thedeflecting properties of implant strip 2300.

Implant strip 2300 also preferably includes slots 2302. In thisembodiment, slots 2302 extend from upper side 2304 to lower side 2306 ofimplant strip 2300. Slots 2302 preferably extend through protrudingportion 2303. The addition of slots 2302 to implant strip 2300 generallydecreases the rigidity of protruding portion 2303. Using thisconfiguration, slots 2302 may provide increased deflection of protrudingportion 2303.

FIGS. 29 and 30 are a preferred embodiment of implant strip 2300following implantation. As implant strip 2300 is coiled, implant strip2300 is configured to deflect in the circumferential direction. In apreferred embodiment, the deflection primarily occurs at slots 2302.FIG. 30 illustrates the widening of slots 2302 during coiling. Forexample, first slot 2700 of implant strip 2300 is wider at first end2704 than second end 2702.

FIG. 31 is a preferred embodiment of outer ring 2332 of implant strip2300 undergoing axial deflection. For purposes of clarity, inner rings2330 of implant strip 2300 are shown in phantom. As an axial force isapplied, protruding portion 2303 deflects. In particular, the anglebetween upper side 2304 and first sloped portion 2310 and the anglebetween lower side 2306 and second sloped portion 2312 may change asupper side 2304 and lower side 2306 are squeezed together.

In some embodiments, the number, shape and size of slots associated withan implant strip may vary. By changing the number, shape, orientationand/or size of slots of an implant strip, the axial loadingcharacteristics of the implant strip may be controlled. Increasing thenumber of slots may increase the degree of axial deflection, as therigidity of protruding portion 2303 is reduced with an increasing numberof slots. Likewise, decreasing the number of slots may decrease thedegree of axial deflection, as the rigidity of protruding portion 2303is increased with a decreased number of slots.

Additionally, changing the number of slots may also increase theflexibility of the implant strip in the circumferential direction.Increasing the number of slots may generally increase the amount ofdeflection in the circumferential direction. Likewise, decreasing thenumber of slots may generally decrease the amount of deflection in thecircumferential direction.

FIG. 32 is a preferred embodiment of first implant strip 2800 and secondimplant strip 2804. First implant strip 2800 includes first slots 2802and second implant strip 2804 includes second slots 2806. Preferably,the number of slots comprising first slots 2802 is greater than thenumber of slots comprising second slots 2806.

Referring to FIG. 33, first implant strip 2800 and second implant strip2804 have different deflection characteristics since first implant strip2800 has a greater number of slots than second implant strip 2804. Inthis embodiment, first implant strip 2800 can deflect or curve more inthe circumferential direction than second implant strip 2804. Inparticular, first implant strip 2800 has a first radius of curvature R1than is smaller than a second radius of curvature R2 associated withsecond implant strip 2804.

By varying the radius of curvature of an implant strip in this manner,the tightness of coiling associated with an implant strip may be varied.Generally, a tighter coil provides more surface area over which toreceive axial loads from adjacent vertebrae and thereby increases thestrength of the implant strip in the axial direction.

In the previous embodiment, slots of different widths are used tomodifying the deflecting properties of an implant strip. In otherembodiments, the spacing between slots could vary. In still otherembodiments, the orientation of the slots may vary as well.Additionally, in some embodiments, the slots could have different shapessuch as oval, round, hexagonal or any type of polygon or irregularshape. These various shapes can be used singularly or in any desiredcombination.

In another embodiment, shown in FIG. 34, a portion of implant strip 3300includes a variety of punched out shapes configured to change thedeflecting characteristics of implant strip 3300. In some embodiments,implant strip 3300 may include thin slots 3302 and wide slots 3304. Inthis embodiment, the spacing between slots varies from spacing S1 tospacing S2. In this exemplary embodiment, spacing S1 is much larger thanspacing S2. In other embodiments, the spacing between slots could be anylength, and could vary over implant strip 3300.

In some cases, the orientation of slots could be modified. In someembodiments, implant strip 3300 may include angled slots 3310.Generally, angled slots 3310 may be oriented in any direction,including, in other embodiments, perpendicular to thin slots 3302.

Additional shapes for cutouts are also illustrated in FIG. 34. In someembodiments, implant strip 3300 may include circular cutouts 3312,triangular cutouts 3314 or diamond cutouts 3315. Furthermore, in somecases, the various shapes could be repeating or non-repeating, includingvarious geometric patterns such as honeycomb-like cutouts 3316. In thiscase, the remaining portions of implant strip 3300 may be configured aslattice 3318.

The various shapes and patterns illustrated in FIG. 34 are only meant tobe exemplary. In some embodiments, a single size, shape and spacing forcutouts or slots may be used. In other embodiments, a variety ofdifferent shapes for cutouts or slots including regular or irregularspacing between shapes may be used. By using slots or cutouts of varyingwidths, sizes, orientations and various spacing between slots orcutouts, the deflection properties and the coiling properties of implantstrip 3300 may be tuned.

Preferably, implant strips may be configured to permanently deflect insome situations. Generally, vertebrae are not completely symmetric andtherefore the spacing between two adjacent vertebrae may vary. Using animplant strip that is configured to partially permanently deflect atsome portions allows for a more natural fit of the implant strip.

FIG. 35 is a schematic view of a preferred embodiment of a portion ofspinal column 3100, including vertebrae 3102. Implant strip 3104 hasbeen inserted between vertebrae 3102 to replace a spinal disc. In thisembodiment, the spacing between vertebrae 3102 varies. In particular, atfront side 3106 of spinal column 3100, vertebrae 3102 are separated by aheight H7 while at rear side 3108 of spinal column 3100, vertebrae 3102are separated by a height H8 that is less than height H7. Preferably,implant strip 3104 has partially permanently deflected at rear side3108, allowing for a natural fit. It should be understood that implantstrip 3104 has only partially permanently deflected at rear side 3108.Generally, implant strip 3104 is configured to continue axial deflectionunder increased axial loads at front side 3106 and rear side 3108.

Using the configuration described here, the shape of implant strip 3104is preferably automatically customized. In some regions between adjacentvertebrae, such as the narrow region discussed above, the implant stripmay plastically deform to adjust to natural contours of the adjacentvertebrae. In other regions, such as the wider region discussed above,the implant strip may remain extended or minimally deflected to fullyfill in the spaces between vertebrae. In this manner, the implant strippreferably performs a similar function to a spinal disc.

Preferably, an implant strip may include provisions for facilitatingcoiling of the implant strip during implantation into a spine. In apreferred embodiment, a curved tube may be used to facilitate coiling ofan implant strip. The following embodiment is intended to illustrate aprovision for facilitating coiling of any type of implant strip. Itshould be understood that the following procedure may be used tofacilitate the implantation of any of the various implant stripsdiscussed earlier as well as other possible implant strips.

FIG. 36 is a preferred embodiment of implant strip 2110 being insertedinto cavity 1560 of intervertebral disc 1202. In this embodiment, theinsertion of implant strip 2110 is facilitated by delivery device 2102.Delivery device 2102 may be a catheter or similar tube configured forreceiving implant strip 2110. Preferably, distal end 2104 of deliverydevice 2102 is disposed just inside of cavity 1560 and includes curveddeforming tip 2106.

As implant strip 2110 is inserted, curved deforming tip 2106 helpsfacilitate some bending of implant strip 2110 in the circumferentialdirection. As insertion of implant strip 2110 continues, intermediateportion 2114 of implant strip 2110 is further coiled by inner curvedportion 2108 of delivery device 2102. This arrangement furtherfacilitates the coiling of distal end 2112 of implant strip 2110 towardsthe center of cavity 1560. Using delivery device 2102 allows forincreased control of coiling of implant strip 2110 during implantation.

In some embodiments, a spinal implant strip may be used to repair aherniated intervertebral disc. This may be achieved by using similartechniques for removing the herniated portion of the disc. Followingthis, a spinal implant strip may be inserted into the removed portion ofthe disc.

FIG. 37 is a plan view similar to that of FIG. 2, illustrating aherniated or traumatized intervertebral disc 1202. As shown, the nucleuspulposus 1224 is protruding from the intervertebral disc 1202 through acut or flaw 1204 in the intervertebral disc 1202. The protruding nucleuspulposus 1224 impinges on one of the exiting nerves 1218 as well as thespinal cord 1216 or cauda equina.

In cases where an intervertebral disc is herniated, such as is shownhere, portions of nucleus pulposus 1224 may be removed, as seen in FIG.38. This may be achieved using standard surgical techniques ortechniques similar to those discussed in the previous embodimentsillustrated in FIGS. 6-8. In some cases, a partial discectomy may bealso performed through a single tube or double tube. At this point,recess 3702 is left open within disc annulus 1222.

Preferably, implant strip 3802 may be inserted into recess 3702 torepair intervertebral disc 1202, as seen in FIG. 39. This may beaccomplished using similar techniques to those previously discussed forimplanting a spinal strip illustrated in FIGS. 6-8. As noted in theembodiment shown in FIGS. 6-8, implant strip 3802 may be inserted usinga single tube or double tube technique. Using this preferredarrangement, implant strip 3802 may be configured to replicate themechanical properties of nucleus 1224.

Using the various arrangements for a spinal implant strip discussed inthis detailed description provides for improved utility over priordesigns. Each of these designs is versatile since various types ofimplant strips may be used for replacing various kinds of spinal discs.Also, each of these arrangements provides for a single piece device thatdoes not experience the wear or generate particulate debris that may beassociated with multi-piece designs. Finally, using the materials anddesigns discussed in this detailed description, the implant strips arepreferably configured to either remain rigid or maintain a generalspring-like state, without undergoing any fatigue or mechanical failure.

Embodiments of the present invention can provide for continuity of thespine. The term “continuity of the spine” generally refers to theconcept providing an actual mechanical bridge between two distinctvertebral bodies. In some embodiments, this implant device provides fora mechanical bridge while also allowing motion between the two distinctvertebral bodies. This arrangement can approximate the naturalbiomechanics of the spine.

By applying principles or features of the present invention, a surgeoncan implant a device to restore the original anatomical height of thedisk, thereby restoring normal forces across the spine. The surgeon canalso select an implant device that can provide decompression of thenerves in the spinal foramen and canals. This implant device can providea post-implantation height greater than or less than the originalanatomical height of the disk. This implant device can also provide apost-implantation configuration that optimizes the relative positionbetween two vertebrae. In some cases, this post-implantationconfiguration can be used to correct scoliosis or spondylolisthesis.

While various embodiments of the invention have been described, thedescription is intended to be exemplary, rather than limiting and itwill be apparent to those of ordinary skill in the art that many moreembodiments and implementations are possible that are within the scopeof the invention. Accordingly, the invention is not to be restrictedexcept in light of the attached claims and their equivalents. Also,various modifications and changes may be made within the scope of theattached claims.

1. A spinal prosthesis configured for insertion between two adjacentvertebrae, a first vertebrae and a second vertebrae, comprising: animplant strip including a lateral dimension extending from a firstlateral side portion to a second lateral portion, and wherein theimplant strip includes a longitudinal dimension extending down thelength of the implant strip; wherein the first lateral side of theimplant strip is configured to engage the first vertebrae and whereinthe second lateral side of the implant strip is configured to engage thesecond vertebrae; wherein a first longitudinal portion of the implantstrip forms a first inner coil, and wherein a second longitudinalportion of the implant strip forms a second outer coil, wherein thesecond outer coil is spaced radially outward of the first inner coil. 2.The spinal prosthesis according to claim 1, wherein the first inner coiland the second inner coil are spaced to prevent contact with oneanother.
 3. The spinal prosthesis according to claim 1, wherein thefirst lateral side portion and the second lateral side portion comprisea first portion, and wherein a second portion is disposed between thefirst lateral side portion and the second lateral side portion; andwherein the second portion is less rigid than the first portion.
 4. Thespinal prosthesis according to claim 3, wherein the second portionpermits motion between the first lateral side portion and the secondlateral side portion.
 5. The spinal prosthesis according to claim 4,wherein the first inner coil and the second inner coil are spaced toprevent contact with one another during motion.
 6. The spinal prosthesisaccording to claim 1, wherein the implant strip is corrugated.
 7. Thespinal prosthesis according to claim 1, wherein a plurality of implantstrips are configured for implantation between the first vertebrae andthe second vertebrae.
 8. The spinal prosthesis according to claim 7,wherein three implant strips are configured for implantation between thefirst vertebrae and the second vertebrae.
 9. The spinal prosthesisaccording to claim 1, wherein the coils are spaced apart to allow newbone growth to develop between the coils.
 10. The spinal prosthesisaccording to claim 1, wherein the spinal prosthesis provides forcontinuity of a spine by providing a mechanical bridge between the firstvertebrae and the second vertebrae.
 11. The spinal prosthesis accordingto claim 1, wherein the spinal prosthesis also allows motion between thefirst vertebrae and the second vertebrae.
 12. A spinal prosthesis,configured for insertion between two adjacent vertebrae, a firstvertebrae and a second vertebrae, comprising: a first implant strip anda second implant strip disposed adjacent to one another; and wherein thefirst implant strip and the second implant strip have different heights.13. The spinal prosthesis according to claim 12, wherein the firstimplant strip and the second implant strip are configured to correct adeformity.
 14. The spinal prosthesis according to claim 12, wherein thefirst implant strip and the second implant strip are configured tocreate lordosis.
 15. The spinal prosthesis according to claim 12,wherein the first implant strip and the second implant strip areconfigured to correct scoliosis.
 16. A spinal prosthesis, comprising: animplant strip configured for implantation between two adjacentvertebrae; the implant strip having a first longitudinal dimension and asecond lateral dimension, wherein the first longitudinal dimension isgreater than the second lateral dimension, and wherein the implant stripis configured to coil; a bone growth promoting agent; and wherein thebone growth promoting agent is applied to the implant strip.
 17. Thespinal prosthesis according to claim 16, wherein the implant stripincludes a first portion, and wherein the bone growth promoting agent isapplied to the first portion.
 18. The spinal prosthesis according toclaim 16, wherein the bone growth promoting agent is applied to theentirety of the implant strip.
 19. The spinal prosthesis according toclaim 16, wherein the bone growth promoting agent is selectively appliedto the implant strip.
 20. The spinal prosthesis according to claim 16,wherein the bone growth promoting agent is applied to a top surface ofthe implant strip and a bottom surface of the implant strip.
 21. Thespinal prosthesis according to claim 16, wherein a plurality of bonegrowth promoting agents are applied to the implant strip.